Physico-chemical water treatment

Coagulation, neutralisation & flocculation

This forms the basis of every physico-chemical installation. The aim is to precipitate pollutants into a sludge fraction that can easily be separated.

• Coagulation: The first step, in which we neutralise the electrical charge of particles by dosing a coagulant. 
• Neutralisation: Through precise pH control, often using milk of lime or sodium hydroxide, we form hydroxides that cause unwanted substances to precipitate out of solution. 
• Flocculation: Adding a polyelectrolyte causes micro-flocs to bind together into large, robust flocs that are easier to separate. 

Detoxification

For specific industrial streams containing toxic components, specialised pretreatment is indispensable. We focus on chemical conversion into safe, precipitable forms that can easily be separated.

• Chromium(VI) reduction: We reduce toxic Cr(VI) to the more manageable Cr(III). 
• Cyanide detoxification: Cyanides are rendered harmless by means of a controlled oxidation process. 
• Heavy metals: For metals that do not form hydroxides (such as mercury or arsenic), we use specific reagents. 

pH & redox control

Accurate measurement and control are essential for stable, reliable process operation. Continuous monitoring means deviations are detected immediately and corrected automatically, ensuring efficient chemical consumption without overdosing.

• pH control: We select the right probe specifically for your medium and automate the dosing of acids or alkalis. 
• Redox measurement: Ensures reliable process control during chemical conversion reactions such as oxidation, reduction and detoxification.
• Automation: Our controllers link the measured values directly to the dosing pumps for applications such as chlorine disinfection or chromium reduction. 

Sludge separation

Once the flocs have formed, they must be separated from the treated water. The choice of technology depends on the sludge concentration and the flow rate.

• Settling (sedimentation): The classic method, in which sludge is separated at the bottom of the installation. 
• Lamella clarifier: Ideal where space is limited; inclined plates increase the effective settling area, allowing us to handle high flow rates on a minimal footprint. 
• Flotation (DAF): An alternative in which micro air bubbles carry the sludge to the surface. Ideal for light sludge or high hydraulic loads. 

Post-treatment

As a final step, post-treatment can be used to remove residual contaminants from the water and guarantee a consistent final quality.

• Sand filtration: removes residual suspended solids and fine particles from the treated water.
• Activated carbon filtration: adsorbs dissolved organic substances as well as colour, odour and taste compounds, and can be used to target specific residual contaminants.

Depending on the required water quality, both techniques can be applied separately or in combination.

Dewatering

The separated sludge still contains a large amount of water. Dewatering the sludge further greatly reduces its volume and keeps transport and disposal costs down.

• Chamber filter press: presses the sludge between filter plates under pressure, forming a relatively dry filter cake.
• Centrifuge: continuously separates water and solids based on their difference in density.
• Vacuum belt filter: continuously dewaters the sludge by drawing it over a filter cloth using vacuum.

The most suitable technique is selected based on factors including the sludge type, the sludge volume and the required dry solids content.